1. Field of the Invention
This invention relates to the field of noncellular elastomers. The elastomers are polyurethanes prepared from polyhydroxyl compounds and a specific aromatic diisocyanate.
2. Description of the Prior Art
The preparation of polyurethane elastomers by reacting essentially linear higher molecular weight polyhydroxyl compounds such as hydroxyl group-containing polyesters of alkylene glycols and aliphatic dicarboxylic acids or hydroxy carboxylic acids or hydroxyl group-containing polyethers based on polytetrahydrofuran, chain extenders such as short chained diols or diamines and organic diisocyanates such as 1,6-hexamethylene diisocyanate, isophorone diisocyanate, 2,4-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate and 1,5-naphthylene diisocyanate is the subject of numerous publications. These polyurethane elastomers are clearly described, for example, in the Plastics Handbook, vol. VII, Polyurethanes by R. Vieweg and H. Hoechtlen, Carl Hanser Publishers, Munich 1966, starting at page 206, or Plastics 68 (1978) 12, pages 819-825.
British Pat. No. 1,069,602 describes coating agents with improved light fastness for the preparation of which adducts of 4,4'-, 2,4'- and 2,2'-diisocyanato-1,2-diphenylethane or mixtures of the mentioned isomers and trimethylolpropane, hexane triol or pentaerythritol are reacted with polyoxyalkylene glycols having molecular weights from 550 to 20,000. Coating agents produced in this manner do not contain any or only small quantities of crystalline polymer segments and are, therefore, not suited for the preparation of molded polyurethane elastomer parts.
With a number of very important applications where the material is exposed to extreme dynamic or thermal stresses such as, for example, in highly stressed track rollers, tires and wheels, vibration dampening molded parts in machine and vehicle construction, torsionally elastic couplings, polyurethane elastomers based on 4,4'-diphenylmethane diisocyanate prove to be deficient. To date the very expensive 1,5-naphthylene diisocyanate or physiologically extremely hazardous chain extenders such as 3,3'-dichloro-4,4'-diaminodiphenylmethane had to be used for such applications.